These days, portable type, small computers have been widely used, wherein flexible or floppy disks, electronic cards, etc. are hereinafter called "auxiliary memories". A memory capacity of such a flexible disk, an electronic card, etc. is approximately 1M bytes.
In the operation of a computer, a program of a form which is hereinafter called a "conducting form" is read from an auxiliary memory and is loaded into a main memory of the computer.
However, the amount of program files which are stored in such an auxiliary memory having a capacity of 1M bytes is limited. For instance, even if a program is simple, it often needs 100 to 200 K bytes. In a simple calculation, only five to ten programs are stored in one flexible disk of 1M bytes.
In order to store program files as much as possible into an auxiliary memory, a program is comnpressed to save memory space in accordance with the replacement of repetitive data and the same data or simple data which reappears frequently. Such a compressed program file is developed to be restored in the form of an original program file which is practically used in a computer in response to using a "developing program". Otherwise, such a compressed program is directory extended and developed in a main memory of a computer in order to be run, carried out, or "conducted" in the computer.
In general, programs which are to be frequently used or which are grouped library are preferable to be stored in a common auxiliary memory. In case of using a computer such as a portable computer with which a large capacity of an auxiliary memory can not be utilized, the auxiliary memories must be replaced by each other, when a program to be conducted is changed.
In case of storing a program which is compressed, the program must be developed, when it is conducted. Otherwise, a particular computer in which a compressed program is conducted is required. In this case, however, the size of the compressed program is generally limited.